1. Field of the Invention
The present invention is directed to a method of detecting faults or defects in a plurality of electrical networks in an electrical component such as a substrate, preferably using contactless methods of electrical testing.
2. Description of Related Art
Test and inspection are keys in reducing costs and increasing functionality of electrical networks in an electrical component. For example, VLSI chip packaging densities require finer line widths and more substrate interconnection networks which are taxing conventional methods of testing. While the present invention provides a test method which is not restricted to any particular test system, it is particularly advantageous for use with non-destructive methods of in-process testing such as voltage contrast electron beam testing by any suitable apparatus such as disclosed in U.S. Pat. No. 4,829,243.
The present invention is directed to a method of testing networks having a plurality of nodes by (1) electrically charging one of the nodes in the network and testing the other nodes for electrical charges for measuring continuity or opens in the network and (2) detecting shorts in the network by finding voltages on the network which are not intentionally charged.
The present invention is further directed to a method of testing in which various levels of testing may be performed for detecting various levels of electrical faults. The method provides a compromise between various levels of testing depending upon the trade-off desired between reducing testing costs or obtaining information about faults.